1. Field of the Invention
The present invention relates to a disk apparatus for recording and/or reproducing information on disks such as CDs (compact disks) and DVDs (digital versatile disks), and more particularly, to a disk apparatus including locating means for locating disks on a turntable, and a method of locating/discriminating the disks using the disk apparatus.
2. Description of the Related Art
FIG. 11 illustrates the concept of a conventional disk apparatus.
Referring to FIG. 11, a conventional disk apparatus A has a disk inserting opening 1 in the front (the negative side of the Y axis) thereof, and a disk transport mechanism such as a disk transport roller 2 is provided behind the disk inserting opening 1.
An optical detecting means 4 having a plurality of photo sensors 4a aligned thereon is provided between the disk inserting opening 1 and the transport roller 2. Each photo sensor 4a consists of, for example, a pair of optical members consisting of a light emitting element provided on the side of a cover covering the disk apparatus A and a light receiving element provided on a bottom plate. The photo sensors 4a are aligned in the direction of the X axis perpendicular to the insertion direction (the direction of the Y axis) of a disk D. Thus, when the disk D is inserted into the disk apparatus from the disk inserting opening 1, outputs of the light receiving elements are reversed because light between the light emitting elements and the light receiving elements is blocked. There is difference in the number of the light receiving elements having the reversed outputs due to the difference in diameter of disks such as between an SD (single disk) of 8 cm in diameter and a CD (compact disk) of 12 cm in diameter. Thus, by detecting the number of the light receiving elements having the reversed outputs, the diameter of a disk D, i.e., the SD or the CD is discriminated, and the discrimination data are transmitted to a control section.
A pair of stopper pins 5a and 5b are provided behind a disk driving section 3 having a turntable Ta. The stopper pins 5a and 5b are fixed on a plate (not shown) and are slidable only in the disk transport direction (the direction of the Y axis). When the disk D is not placed in the disk apparatus A, the stopper pins 5a and 5b are aligned at positions (a) close to the disk driving section 3. Therefore, the disk D inserted from the disk inserting opening 1 is transported in the positive direction of the Y axis by the transport roller 2 so as to abut against the stopper pins 5a and 5b. A transporting force for transporting the disk D in the positive direction of the Y axis is continuously applied on the stopper pins 5a and 5b even after the disk D has been abutted against the stopper pins 5a and 5b. Thus, the stopper pins 5a and 5b are pressed by the disk D to move in the positive direction of the Y axis together with the disk D.
However, since the diameter of the disk D has already been discriminated as described above, the moving distance of the stopper pins 5a and 5b responsive to the SD or the CD is controlled by a command from the control section based on the discrimination data. That is, the movement of the stopper pins 5a and 5b is stopped by electrical or mechanical means when the stopper pins 5a and 5b reach predetermined positions. At this time, a center hole D0 of the disk D is located over the turntable Ta of the disk driving section 3. For example, in case the inserted disk D is the SD, the stopper pins 5a and 5b are stopped at positions (b) where they move from the positions (a). In case the inserted disk D is the CD, the stopper pins 5a and 5b are stopped at positions (c) where they move from the positions (a).
The disk D thus transported over the turntable Ta is released from a condition clamped by the transport rollers 2 to be placed on the turntable Ta. Then, the disk D is clamped by a clamp mechanism, etc. on the turntable Ta, and a rotation force due to a motor M provided in the disk driving section 3 is imparted thereto. In addition, information recorded in the disk D is reproduced and/or information is recorded in the disk D by a head member (not shown) which is movable in the radial direction of the disk placed on the turntable Ta.
The above conventional disk apparatus A encounters the following problems.
The first problem relates to the discrimination of the disk D at the time of disk insertion. That is, since it is necessary to provide a plurality of photo sensors 4a consisting of light emitting elements and light receiving elements behind the disk inserting opening 1 in order to discriminate the diameter of the disk D, the number of components increases, thereby increasing the cost of manufacturing the disk apparatus A. In addition, since dust is most likely to enter the place near the disk insertion opening 1, the surfaces of the light emitting elements and the surfaces of the light receiving elements of the photo sensors 4a are contaminated after being used for a long time, so that the detection ability may deteriorate.
Further, if a small number of photo sensors 4a are used for discriminating the diameter of the disk D, resolution decreases. Also, even if foreign matter other than the disk is inserted from the disk inserting opening 1, disk insertion is erroneously detected, so that the transport rollers 2 may be driven to transport the foreign matter into the disk apparatus A.
The second problem relates to reliability when locating the disk D on the turntable Ta.
A distance d between the pair of the stopper pins 5a and 5b is set narrower than the disk D of the smallest diameter (8 cm) such as the SD, and the disk D inserted from the disk inserting opening 1 solidly abuts against the stopper pins 5a and 5b.
However, in case the disk D is inserted into the disk inserting opening 1 in such a manner that it is shifted leftward or rightward from the center of the disk inserting opening 1, the disk D is transported by the transport roller 2 in this shifted condition. The periphery of the disk D may abut against only one of the stopper pins 5a and 5b. In this case, since the disk D is not located at a correct position when the stopper pins 5a and 5b stop, the disk D cannot be placed accurately on the turntable Ta, and therefore the disk D cannot be driven.